Browsing by Author "Lu, Hau-Yan"

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A new pixel circuit compensating for brightness variation in lagre size and high resolution AMOLED displays
(2007-12-01)
Lu, Hau-Yan
;
Chang, Ting-Chang
;
Tai, Ya-Hsing
;
Liu, Po-Tsun
;
Chi, Sien
A new pixel design and driving method for active-matrix organic light-emitting diode (AMOLED) display using low-temperature polycrystalline silicon thin-film transistor (LTPS-TFT) is proposed. The new circuit consists, of five TFTs and one capacitor to eliminate the variation in the threshold voltage of the TFTs, and the drop in the supply voltage in it single frame operation. The proposed pixel circuit has been verified to realize uniform output current by the simulation work using HSPICE software. The simulated error rate of the output current is also discussed in this paper. The novel pixel design has great potential for use in large size and high resolution AMOLED displays.
A novel a-Si TFT pixel circuit with high immunity to the degradation of the TFTs and OLEDs used in AMOLED displays
(2007)
Lu, Hau-Yan
;
Liu, Po-Tsun
;
Hu, Chin-Wei
;
Chang, Ting-Chang
;
Chi, Sien
A simple pixel circuit employing a-Si TFT for AMOLED is proposed. The proposed one can eliminate both the threshold voltage shift of the driving TFT and the OLED. The simulation results indicate that the proposed circuit significantly improves the non-uniformity of output current by the new compensation operation.
A novel threshold voltage compensation pixel circuit with high immunity to the supply voltage drop for AMOLED displays
(2006)
Lu, Hau-Yan
;
Liu, Po-Tsun
;
Chang, Ting-Chang
;
Chi, Sien
;
光電工程學系
A new pixel circuit employing LTPS TFT for AMOLED is proposed. The proposed one can eliminate both the threshold voltage variation of the driving TFT and the supply voltage drop. The simulation results indicate that the proposed circuit significantly improves the non-uniformity of output current by the new compensation operation.
Electrical degradation of N-channel poly-Si TFT under AC stress by C-V measurement
(2007)
Lu, Hau-Yan
;
Liu, Po-Tsun
;
Chang, Ting-Chang
;
Chi, Sein
;
光電工程學系
The electrical degradation of n-channel poly-silicon thin film transistor (poly-Si TFT) has been investigated under dynamic voltage stress by capacitance-voltage (C-V) measurement. In C-V measurements, the fixed charges in the gate oxide film of TFTs are not affected by the applied small signal, whereas the trap states in the band gap would respond to the applied frequency, so that the dominant degradation mechanism of poly-Si TFTs can be evaluated. Our experimental results show that the degradation of n-type TFTs is caused by additional trap states located at the drain and the source junction in the poly-Si thin film. Furthermore, through the experimental results of the C-V characteristics measured at 10 kHz and 1 MHz, we can infer that the tail states produced by the strained bounding in poly-Si film are mostly responsible for the electrical degradation of n-channel poly-Si TFTs after dynamic stress.
Elimination of photoleakage current in poly-Si TFTs using a metal-shielding structure
(2008)
Lu, Hau-Yan
;
Chang, Ting-Chang
;
Liu, Po-Tsun
;
Li, Hung-Wei
;
Hu, Chin-Wei
A technology to eliminate the photoleakage current of poly-Si thin-film transistors (TFTs) with top gate structure has been developed. A thin metal film is formed on the glass substrate to be used as a light-shielding layer. The light-shielding layer, buffer layer, and active island are patterned employing the same mask. The leakage current and the variation of subthreshold swing in the proposed devices are suppressed completely under illumination. Due to the parasitic capacitance in the overlap region between the drain side and the metal-shielding layer, a floating voltage coupled from drain bias influences the threshold voltage of the proposed poly-Si TFTs. (c) 2008 The Electrochemical Society.
Enhancement of brightness uniformity by a new voltage-modulated pixel design for AMOLED displays
(2006-09-01)
Lu, Hau-Yan
;
Liu, Po-Tsun
;
Chang, Ting- Chang
;
Chi, Sien
;
光電工程學系
This letter presents a new pixel design and driving method for active-matrix organic light-emitting diode (AMOLED) displays using low-temperature polycrystalline silicon thin-film transistors (TFTs). The proposed pixel circuit consists of five TFTs and one capacitor to eliminate the 'variation in the threshold voltage of the TFTs, and the drop in the supply voltage in a single frame operation by the source-follower-type connection and the bootstrap. The proposed pixel circuit has been verified to realize uniform output current by the simulation work using the HSPICE software. The novel pixel design has great potential for use in large-size and high-resolution AMOLED displays.
Layout dependence on threshold voltage instability of hydrogenated amorphous silicon thin film transistors
(2007-03-01)
Tseng, Huai-Yuan
;
Chiang, Ko-Yu
;
Lu, Hau-Yan
;
Kung, Chen-Pang
;
Chang, Ting-Chang
In this paper, we discuss the threshold voltage instability of two distinct layouts of hydrogenated amorphous silicon thin film transistors (a-Si:H TFTs). By simultaneously applying gate and drain bias stress, we show that the average threshold voltage shift of circular a-Si:H TFTs is 54% less than that of conventional inverted staggered a-Si:H TFTs. This result is primarily due to that the circular layout reduces the channel electron concentration. ISE-DESSIS (Integrated System Engineering DEvice Simulation for Smart Integrated Systems) was used to simulate the parallel electric field and obtain the total channel electron concentration. The simulation results closely correspond to the explanation in this study. These results indicate a significant impact of improving threshold voltage stability by a layout method.
Reduction of photoleakage current in polycrystalline silicon thin-film transistor using NH(3) plasma treatment on buffer layer
(2008-04-14)
Lu, Hau-Yan
;
Chang, Ting-Chang
;
Liu, Po-Tsun
;
Li, Hung-Wei
;
Hu, Chin-Wei
The technology of polycrystalline silicon thin-film transistors (poly-Si TFTs) with low photoleakage current is developed in this work. The electrical characteristics of poly-Si TFTs under illumination were significantly improved employing the NH(3) plasma treatment on the buffer layer, with no need for complicate device structure and additional masks. The trap states that originated from the plasma bombardment on the interface between the poly-Si layer and buffer oxide can effectively recombine the light-induced electron-hole pairs. The fewer residual electron-hole pairs lead to the lower photoleakage current and improved subthreshold swing, as well as maintaining good electrical characteristics in the dark sate. (C) 2008 American Institute of Physics.
Reduction of photoleakage current in polycrystalline silicon thin-film transistor using NH3 plasma treatment on buffer layer
(2008-04-14)
Lu, Hau-Yan
;
Chang, Ting-Chang
;
Liu, Po-Tsun
;
Li, Hung-Wei
;
Hu, Chin-Wei
The technology of polycrystalline silicon thin-film transistors (poly-Si TFTs) with low photoleakage current is developed in this work. The electrical characteristics of poly-Si TFTs under illumination were significantly improved employing the NH3 plasma treatment on the buffer layer, with no need for complicate device structure and additional masks. The trap states that originated from the plasma bombardment on the interface between the poly-Si layer and buffer oxide can effectively recombine the light-induced electron-hole pairs. The fewer residual electron-hole pairs lead to the lower photoleakage current and improved subthreshold swing, as well as maintaining good electrical characteristics in the dark sate. (C) 2008 American Institute of Physics.
Study on degradation of crystallized laterally grown poly-Si TFT under Dynamic Stress
(2007)
Lu, Hau-Yan
;
Chung, Wan-Fang
;
Tseng, Tzu-Yi
;
Chen, Yu-Cheng
;
Liu, Po-Tsun
The influence of protrusion grain boundary on the degradation of crystallized laterally grown poly-Si TFT under Dynamic Stress is investigated. The degradation of TFT with protrusion grain boundary is more severe and the different damage of the source/drain junction in the TFT with grain boundary closed to source side.